It is probably just feeding or on the way to feed. It sounds like it is doing what bats do. That is flying around looking for food. If the bat has made a home near by, or made your yard a stop for feeding you will see it often. Nothing to worry about.

Bats are a good thing to have around, they keep the insect population under control in your yard.

The bats around here will get fairly close too, but never actually touch anyone. At least on purpose.

It could be that it just likes your pool.